[PATCH v2 1/4] iov_iter: Provide copy_iomem_to|from_iter()

[kernel test robot]

Hi Michal,

kernel test robot noticed the following build warnings:

[auto build test WARNING on drm-xe/drm-xe-next]
[also build test WARNING on brauner-vfs/vfs.all akpm-mm/mm-nonmm-unstable linus/master v6.12-rc7 next-20241113]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Michal-Wajdeczko/iov_iter-Provide-copy_iomem_to-from_iter/20241113-080831
base:   https://gitlab.freedesktop.org/drm/xe/kernel.git drm-xe-next
patch link:    https://lore.kernel.org/r/20241112200454.2211-2-michal.wajdeczko%40intel.com
patch subject: [PATCH v2 1/4] iov_iter: Provide copy_iomem_to|from_iter()
config: x86_64-randconfig-123-20241113 (https://download.01.org/0day-ci/archive/20241114/202411140935.iEbIWcpc-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241114/202411140935.iEbIWcpc-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp at intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202411140935.iEbIWcpc-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> lib/iov_iter.c:373:47: sparse: sparse: cast removes address space '__iomem' of expression
   lib/iov_iter.c:386:47: sparse: sparse: cast removes address space '__iomem' of expression
>> lib/iov_iter.c:349:33: sparse: sparse: incorrect type in argument 2 (different address spaces) @@     expected void const volatile [noderef] __iomem * @@     got void * @@
   lib/iov_iter.c:349:33: sparse:     expected void const volatile [noderef] __iomem *
   lib/iov_iter.c:349:33: sparse:     got void *
   lib/iov_iter.c:330:37: sparse: sparse: incorrect type in argument 2 (different address spaces) @@     expected void const volatile [noderef] __iomem * @@     got void * @@
   lib/iov_iter.c:330:37: sparse:     expected void const volatile [noderef] __iomem *
   lib/iov_iter.c:330:37: sparse:     got void *
>> lib/iov_iter.c:362:21: sparse: sparse: incorrect type in argument 1 (different address spaces) @@     expected void volatile [noderef] __iomem * @@     got void *to @@
   lib/iov_iter.c:362:21: sparse:     expected void volatile [noderef] __iomem *
   lib/iov_iter.c:362:21: sparse:     got void *to
>> lib/iov_iter.c:338:24: sparse: sparse: incorrect type in argument 1 (different address spaces) @@     expected void volatile [noderef] __iomem * @@     got void * @@
   lib/iov_iter.c:338:24: sparse:     expected void volatile [noderef] __iomem *
   lib/iov_iter.c:338:24: sparse:     got void *

vim +/__iomem +373 lib/iov_iter.c

   333	
   334	static __always_inline
   335	size_t memcpy_iomem_from_iter(void *iter_from, size_t progress, size_t len,
   336				      void *to, void *priv2)
   337	{
 > 338		memcpy_toio(to + progress, iter_from, len);
   339		return 0;
   340	}
   341	
   342	static __always_inline
   343	size_t copy_iomem_to_user_iter(void __user *iter_to, size_t progress,
   344				       size_t len, void *from, void *priv2)
   345	{
   346		unsigned char buf[SMP_CACHE_BYTES];
   347		size_t chunk = min(len, sizeof(buf));
   348	
 > 349		memcpy_fromio(buf, from + progress, chunk);
   350		chunk -= copy_to_user_iter(iter_to, progress, chunk, buf, priv2);
   351		return len - chunk;
   352	}
   353	
   354	static __always_inline
   355	size_t copy_iomem_from_user_iter(void __user *iter_from, size_t progress,
   356					 size_t len, void *to, void *priv2)
   357	{
   358		unsigned char buf[SMP_CACHE_BYTES];
   359		size_t chunk = min(len, sizeof(buf));
   360	
   361		chunk -= copy_from_user_iter(iter_from, progress, chunk, buf, priv2);
 > 362		memcpy_toio(to, buf, chunk);
   363		return len - chunk;
   364	}
   365	
   366	size_t copy_iomem_to_iter(const void __iomem *from, size_t bytes, struct iov_iter *i)
   367	{
   368		if (WARN_ON_ONCE(i->data_source))
   369			return 0;
   370		if (user_backed_iter(i))
   371			might_fault();
   372	
 > 373		return iterate_and_advance(i, bytes, (void *)from,
   374					   copy_iomem_to_user_iter,
   375					   memcpy_iomem_to_iter);
   376	}
   377	EXPORT_SYMBOL(copy_iomem_to_iter);
   378	

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